Add support for Rewrite JS Scripts in webctrl.ini.

Added by keys beginning with "Rewrite", ie:

RewriteDetail=var n=http_request.request_string.replace(/_detail\/(.*)/,"lib/exe/detail.php?media=$1"); if(n != http_request.request_string) { http_request.request_string=n; true }

If the expression returns "true", reparses http_request.request_string as
an internal redirect.

I plan to have another key that will pre-execute a script from a file so that
these don't need to be an entire script on one line in the INI file.

This API is subject to change.

May contain peanuts.